wehub-resource-sync
48 lines
1.7 KiB
TypeScript
48 lines
1.7 KiB
TypeScript
/**
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* Cursor encoding for keyset pagination over `(created_at, run_id)`.
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*
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* The list query orders by the composite key `(created_at, run_id)`, so a sound
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* cursor must carry BOTH components — cutting on `run_id` alone re-includes and
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* skips rows whenever `run_id` order diverges from `created_at` order.
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*
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* A cursor is an opaque URL-safe base64 token wrapping `{ c: createdAtMs, r:
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* runId }`. Cursors are server-issued (the SDK just echoes
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* `pagination.next`/`previous` back), so this format needs no client update.
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*
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* Legacy cursors were the bare internal run_id (a cuid). They are detected by
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* decode failure: a cuid base64-decodes to non-JSON bytes, so it falls through
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* to `{ kind: "legacy" }` and the old (knowingly unsound) `run_id`-only
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* predicate. In-flight legacy cursors keep working and drain naturally.
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*/
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import { z } from "zod";
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export type DecodedRunsCursor =
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| { kind: "composite"; createdAt: number; runId: string }
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| { kind: "legacy"; runId: string };
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// `c` = created_at (ms since epoch), `r` = run_id. Short keys keep the token small.
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const CompositeCursor = z.object({
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c: z.number().int(),
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r: z.string().min(1),
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});
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export function encodeRunsCursor(createdAtMs: number, runId: string): string {
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return Buffer.from(JSON.stringify({ c: createdAtMs, r: runId })).toString("base64url");
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}
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export function decodeRunsCursor(cursor: string): DecodedRunsCursor {
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try {
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const parsed = CompositeCursor.safeParse(
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JSON.parse(Buffer.from(cursor, "base64url").toString("utf8"))
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);
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if (parsed.success) {
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return { kind: "composite", createdAt: parsed.data.c, runId: parsed.data.r };
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}
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} catch {
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// JSON.parse threw — not a composite cursor.
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}
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return { kind: "legacy", runId: cursor };
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}
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